Valve prosthesis and method for delivery

ABSTRACT

In some embodiments, a valve prosthesis includes an inlet portion that is substantially s-shaped and configured to engage the floor of the outflow tract of the native heart atrium. In some embodiments, a valve prosthesis includes a chordae guiding element configured to reduce bending of the chordae to reduce stress on the chordae during the cardiac cycle. In some embodiments, a valve prosthesis includes a central portion having an hourglass shape configured to pinch a native annulus in order to provide axial fixation of the valve prosthesis within a valve site. In some embodiments, a valve prosthesis includes a frame having an outflow end that is flared to provide a gap between an outflow end of the frame and an outflow end of prosthetic leaflets when the prosthetic leaflets are fully opened.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of prior application Ser. No.14/962,824, filed Dec. 8, 2015, now U.S. Pat. No. 9,867,698, which is adivisional of application Ser. No. 13/736,460, filed Jan. 8, 2013, nowU.S. Pat. No. 9,232,995. The disclosures of which are incorporated byreference herein in their entirety.

BACKGROUND Field

Certain embodiments of the present invention are related to artificialheart valve prostheses, frames, and methods of delivery thereof.

Background Art

Diseased or otherwise deficient cardiac valves can exhibit pathologiessuch as regurgitation and stenosis. Such valves can be repaired orreplaced with prosthetic heart valves using a variety of techniques. Forexample, an open-heart surgical procedure can be conducted during whichthe heart can be stopped while blood flow is controlled by a heart-lungbypass machine. Alternatively, a minimally invasive percutaneoustechnique can be used to repair or replace a cardiac valve. For example,in some percutaneous techniques, a valve assembly can be compressed andloaded into a delivery device, which is then passed through a body lumenof the patient to be delivered to the valve site. There is a continuousneed for improved valve prostheses for use in such techniques.

BRIEF SUMMARY

In some embodiments, a valve prosthesis for implantation into a nativecardiac valve site of an individual can include a valve body and a framesupporting the valve body. The frame can include an inlet portionconfigured to engage the floor of the outflow tract of the native heartatrium and restrict movement of the valve prosthesis in a downstreamdirection of blood flow at the valve site. In some embodiments, theinlet portion can be substantially s-shaped.

In some embodiments, a valve prosthesis includes a valve body and aframe supporting the valve body. The frame can include a central portionconfigured to fit securely within an annulus of the valve site, asupport arm extending from the central portion and configured to extendover and secure a native valve leaflet, and a chordae guiding elementextending from the support arm and configured to engage chordae of thevalve site. The chordae guiding element can be configured to angle thechordae so that the chordae are stretched to restrict movement of thevalve prosthesis in an upstream direction of blood flow at the valvesite. The chordae guiding element can be configured to reduce bending ofthe chordae to reduce stress on the chordae during the cardiac cycle.

In some embodiments, a valve prosthesis can include a valve body and aframe supporting the valve body. The frame can include a central portionconfigured to fit securely within an annulus of the native valve site.The central portion can have an hourglass shape configured to pinch theannulus in order to provide axial fixation of the valve prosthesiswithin the valve site.

In some embodiments, a valve prosthesis can include a valve bodyincluding prosthetic leaflets and a frame secured to the valve body. Theframe can include an inlet portion configured to engage the floor of anoutflow tract of the native heart atrium and restrict movement of theframe in a downstream direction of blood flow at the valve site. Theframe can also include a central portion connected to the inlet portionand configured to fit securely within the native valve annulus. Portionsof the outflow end of the frame can be flared to provide a gap betweenan outflow end of the frame and an outflow end of the prostheticleaflets when the prosthetic leaflets are fully opened.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying figures, which are incorporated herein, form part ofthe specification and illustrate embodiments of a valve prosthesis frameand delivery system. Together with the description, the figures furtherserve to explain the principles of and to enable a person skilled in therelevant art(s) to make, use, and implant the valve prosthesis describedherein.

FIG. 1 illustrates a front view of a simplified drawing of a heart valveprosthesis in accordance with an embodiment implanted within a mitralvalve annulus.

FIG. 2 illustrates a cross-sectional view of a frame in accordance withan embodiment.

FIG. 3 illustrates a front view of a frame in accordance with anembodiment.

FIGS. 4a-b illustrate views of the frame of FIG. 3 implanted in a nativemitral valve site.

FIG. 5 illustrates a front view of a valve prosthesis in accordance withan embodiment.

FIG. 6 illustrates a top view of the valve prosthesis of FIG. 5.

FIG. 7 illustrates a front view of a valve prosthesis in accordance withan embodiment.

FIG. 8 illustrates a top view of the valve prosthesis of FIG. 7.

FIGS. 9a-b illustrate views of the valve prosthesis of FIG. 7 implantedin a native valve site.

FIG. 10 illustrates a bottom-front perspective view of a valveprosthesis in an open position in accordance with an embodiment.

FIG. 11 illustrates a bottom-front perspective view of the valveprosthesis of FIG. 10 in a closed position.

FIG. 12 illustrates a bottom-front perspective view of a valveprosthesis in an open position in accordance with an embodiment.

FIG. 13 illustrates a bottom view of the valve prosthesis of FIG. 12.

FIG. 14 illustrates a bottom-front perspective view of a valveprosthesis in an open position in accordance with an embodiment.

FIG. 15 illustrates a bottom view of the valve prosthesis of FIG. 14.

FIG. 16a illustrates a frame in accordance with an embodiment.

FIG. 16b illustrates a saddle shape formed when the frame of FIG. 16a isexpanded.

FIG. 17 illustrates a front view of a frame in accordance with anembodiment.

FIG. 18 illustrates a top view of the frame of FIG. 17.

FIG. 19 illustrates a simplified drawing of a portion of a frame inaccordance with an embodiment.

DETAILED DESCRIPTION

The following detailed description refers to the accompanying figureswhich illustrate several embodiments. Other embodiments are possible.Modifications can be made to the embodiments described herein withoutdeparting from the spirit and scope of the present invention. Therefore,the following detailed description is not meant to be limiting.

FIG. 1 illustrates a front view of a simplified drawing of a heart valveprosthesis 10 implanted within a mitral valve annulus 12 of a mitralvalve site 14. Valve prosthesis 10 can be configured to be implanted inannulus 12 to replace the function of a native heart valve, such as theaortic, mitral, pulmonary, or tricuspid heart valve. In someembodiments, a single valve prosthesis 10 can be designed for use withmultiple heart valves.

Heart valve prosthesis 10 includes a frame 16 that supports a prostheticvalve body (not shown). The valve body can be formed, for example, fromone or more biocompatible synthetic materials, synthetic polymers,autograft tissue, homograft tissue, xenograft tissue, or one or moreother suitable materials. In some embodiments, the valve body can beformed, for example, from bovine, porcine, equine, ovine, and/or othersuitable animal tissues. In some embodiments, the valve body can beformed, for example, from heart valve tissue, pericardium, and/or othersuitable tissue. In some embodiments, the valve body can comprise one ormore valve leaflets. For example, the valve body can be in the form of atri-leaflet bovine pericardium valve, a bi-leaflet valve, or anothersuitable valve. In some embodiments, the valve body can comprise threeleaflets that are fastened together at enlarged lateral end regions toform commissural joints, with the unattached edges forming coaptationedges of the valve body. The leaflets can be fastened to a skirt, whichin turn can be attached to the frame. The upper ends of the commissurepoints can define an outflow portion corresponding to an outflow end 18of valve prosthesis 10. The opposite end of the valve can define aninflow or distal portion corresponding to an inflow end 20 of valveprosthesis 10. As used herein the terms “distal” or “outflow” areunderstood to mean downstream to the direction of blood flow. The terms“proximal” or “inflow” are understood to mean upstream to the directionof blood flow.

In some embodiments, frame 16 itself can be formed entirely or in partby a biocompatible material. In some embodiments, one or more portionsof frame 16 can be self-expandable and/or balloon expandable. Forexample, one or more portions of frame 16 can be formed from a shapememory alloy, such as certain nitinol (nickel titanium) alloys that can,for example, exhibit shape memory and/or superelasticity.

The actual shape and configuration of valve prosthesis 10 can dependupon the valve being replaced. For example, with respect to mitralvalves, during a conventional human cardiac cycle, the fibrous skeleton,anterior and posterior leaflets 22, papillary muscles 24, chordaetendinea 26, atrial wall 28, outflow tract 30, and ventricular wall (notshown) can all interplay to render a competent valve. For example, thecomplex interaction between the leaflets 22, papillary muscles 24, andchordae 26 can help maintain the continuity between theatrio-ventricular ring and the ventricular muscle mass, which can helpprovide for normal functioning of the mitral valve.

In some embodiments, frame 16 can include a support arm 32 extendingfrom a central portion 34 of frame 16 and configured to extend over andsecure leaflet 22. In particular, upon implantation, support arm 32 canbe configured to clamp and immobilize a corresponding leaflet 22, andhold leaflet 22 close to central portion 34. In some embodiments, frame16 can include multiple support arms 32 with each support arm 32corresponding to a separate native leaflet 22.

In some embodiments, proper seating of valve prosthesis 10 withinannulus 12 can be achieved by capturing one or more native leaflets 22with support arms 32. Radial force generated by valve prosthesis 10 inthe atrium against support arms 32 can create a “sandwich effect,” whichin some embodiments can seat valve prosthesis 10 by pinching leaflets 22and atrial tissue against central portion 34.

In some embodiments, support arm 32 can be coated and/or covered with abiocompatible polymer, such as, for example, expandedpolytetrafluoroethylene (ePTFE). In some embodiments, a covering can bea biocompatible fabric or other biocompatible material, such as bovineor porcine pericardium tissue.

In some embodiments, support arm 32 can be sized or shaped to tensionchordae 26. Chordae 26 can connect to leaflets 22 and can act like “tierods” in an engineering sense. In some patients, not only can chordae 26help prevent prolapse of the native leaflets 22 during systole, they canalso help support the left ventricular muscle mass throughout thecardiac cycle. In some embodiments, the tension between chordae 26 andleaflets 22 can serve to prevent frame 16 from lifting into thepatient's atrium. In some embodiments, chordae tension can serve tosubstantially prevent paravalvular leakage. In some embodiments,paravalvular leakage can be substantially prevented by positioning asealing surface of the valve between inflow end 20 and outflow end 18.

In some embodiments, support arms 32 can be sized or shaped to increasevalve stability. Support arm 32 can, for example, serve to substantiallyprevent leaflets 22 from obstructing flow through outflow tract 30. Insome embodiments, support arms 32 can serve to prevent leaflets 22 frominteracting with prosthetic leaflets of valve prosthesis 10. In someembodiments, support arm 32 can position leaflet 22 to minimizingperivalvular leaks and/or maintain proper alignment of the valveprosthesis. In some embodiments, support arm 32 can serve to avoidsystolic anterior mobility and/or maintain valve stability by preventingmigration of the valve into the atrium or ventricle. In someembodiments, support arm 32 can be configured to enhance overall framestrength.

In some embodiments, frame 16 can include an inlet portion 36 configuredto engage floor 38 of the outflow tract of the native heart atrium. Insome embodiments, inlet portion 36 can restrict movement of valveprosthesis 10 in a downstream direction 40 of blood flow at valve site14.

In some embodiments, inlet portion 36 is configured to deform floor 38of the outflow tract in an upstream direction of blood flow at the valvesite. For example, the radial force of central portion 34 on annulus 12can lift floor 38 in an upstream direction to follow the curvature ofinlet portion 36. In some embodiments, inlet portion 36 can beconfigured such lifted annulus 12 causes chordae 26 to be stretchedwithout rupturing. In some embodiments, inlet portion 36 can be sized tocontact the entirety of floor 38 and a portion of atrial wall 28. Oneexample of such a configuration is shown in FIG. 1. In some embodiments,inlet portion 36 is sized to contact a substantial majority of floor 38.Other suitable configurations can be used. In some embodiments, frame 16can be smaller than annulus 12. In some embodiments, such aconfiguration can serve to prevent radial force on frame 16 from annulus12, which can serve to maintain a desired shape of a prosthetic valvesupported within frame 16.

Because valve prosthesis 10 can be used in a portion of the body thatundergoes substantial movement, it can be desirable for one or moreportions of valve prosthesis 10, such as frame 16 to be flexible. Forexample, in some embodiments, at least a portion of inlet portion 36 canhave a flexibility from about 0.8 N/m to about 2 N/m. In someembodiments, at least a portion of inlet portion 36 can have aflexibility of about 1.25 N/m. In some embodiments, inlet portion 36 caninclude one or more diamond-shaped cells. In some embodiments, inletportion 36 can be formed of twisted strands of nitinol.

Central portion 34 of frame 16, which can be configured to conform toannulus 12. In some embodiments, such a configuration can help anchorvalve prosthesis 10 within annulus 12 to prevent lateral movement ormigration of valve prosthesis 10 due to the normal movement during thecardiac cycle of the heart.

Central portion 34 can be shaped to adapt to the specific anatomy of anindividual. For example, in some embodiments, central portion 34 isconfigured to flex and deform so as to mimic a natural cardiac movementof the heart through the cardiac cycle. In some embodiments, centralportion 34 is substantially rigid to avoid flexing or deformation duringthe cardiac cycle.

The shape of central portion 34 can be configured to reduce the risk ofvalve prosthesis migration and perivalvular leakage. In someembodiments, central portion 34 can define a substantially circular,oval, elliptical, saddle-shaped, or non-geometric shape. In someembodiments, central portion 34 can be formed to have a substantiallystraight profile (for example, being substantially cylindrical andparallel to a longitudinal axis of frame 16). Central portion 34 canhave one or more flared portions (for example, diverging away from alongitudinal axis of frame 16).

In some embodiments, central portion 34 can be wider than the nativevalve at annulus 12. In some embodiments, such a configuration canreduce the likelihood of migration of valve prosthesis 10 into theventricle. In some embodiments, such a configuration can improve sealingof valve prosthesis 10 against atrial wall 28. In some embodiments,frame 16 is designed to provide axial fixation by creating tension inthe chordae 26, which can hold inlet portion 36 of frame 16 againstannulus 12. A transition zone between an inflow portion and an outflowportion of frame 16 can provide sealing with the anatomy to preventparavalvular leakage of frame 16. In some embodiments, frame 16 isshaped and sized so as to anchor frame 16 within annulus 12 by itself orin combination with chordae 26.

FIG. 2 illustrates a cross-sectional view of a frame 41 in accordancewith an embodiment. Frame 41 can include a central portion 43 attachedto an inlet portion 45. In some embodiments, inlet portion 45 can besubstantially S-shaped. For example, inlet portion 45 can include one ormore curves, such as curves 47, 49, and 51, which together canapproximate an S-shape. For example, in some embodiments, inlet portion45 includes extension 39 that protrudes in a radially outward directionfrom central portion 43 of frame 41. The substantial “S” shape of inletportion 45 can be formed by extension 39 bending in a first curve 47from inflow end 61 towards outflow end 59, and then bending in a secondcurve 49 back towards inflow end 61. One embodiment of such an S-shapeis shown for example in FIG. 2. In some embodiments, extension 39 canadditionally bend in a third curve 51 towards a radially inwarddirection.

In some embodiments, frame 41 can include an outer diameter 53 ofapproximately 60.37 mm, a valve diameter 55 of approximately 30.42 mm, avalve height 57 between an outflow end 59 of frame 41 and an inflow end61 of frame 41 of approximately 16.97 mm, an effective valve height 63between an outflow end 59 of frame 41 and curve 49 of approximately10.56 mm, an upper s-shape dimension 65 between curve 47 and 49 ofapproximately 3.14 mm, and a lower s-shape dimension 67 between curve 49and the first full node of the valve section from inflow end 61 ofapproximately 2.51 mm.

In some embodiments, inlet portion 45 can be configured to contact apatient's atrial anatomy at a lower point on frame 41 compared toconventional frame designs. In some embodiments, such a configurationcan serve to increase chordal tension. In some embodiments, the shapeand size of inlet portion 45 can be configured to conform to the shapeof the native mitral annulus and left atrium. In some embodiments, sucha configuration can result in varying degrees of deformation (e.g., aflattening) of inlet portion 45, which can serve to create an excellentseal between inlet portion 45 and the native anatomy. In someembodiments, one or more of the above configurations can serve to reduceparavalvular leakage compared to other frame designs.

Inlet portion 45 can be configured to maintain contact throughout apatient's cardiac cycle. In some embodiments, changes in chordal tensioncan be accommodated by partially flattening inlet portion 45. In someembodiments, the flattening of inlet portion 45 can hold a spring load.In some embodiments, as changes in the chordal tension throughout thecardiac cycle occur, the spring load can serve to maintain contact andsealing with the tissue despite the changing tension.

FIGS. 3, 4 a and 4 b illustrate a frame 42. FIG. 3 illustrates a frontview of frame 42. FIG. 4a illustrates a view of frame 42 implanted in anative mitral valve site 44 and FIG. 4b illustrates an enlarged view ofa portion of FIG. 4a . Valve site 44 includes an annulus 46, nativeleaflets 48, chordae 50, and papillary muscles 52.

Frame 42 includes support arms 54, inlet portion 56, and a centralportion 58. A partially hourglass-shaped central portion 58 of frame 42is configured to pinch a muscular ridge of annulus 46 to provide axialfixation of frame 42 within valve site 44. The hourglass shape portionof frame 42 can be located on central portion 58 corresponding to thelocation of the commissures of the native valve within the valve site.One example of such a configuration is shown in FIGS. 3-4. Othersuitable configurations can be used. In some embodiments, a portion ofcentral portion 58 is angled about 90 degrees from the angle of supportarms 54. Frame 42 can also provide axial fixation by creating chordaltension of chordae 50.

FIGS. 5-6 illustrate a valve prosthesis 60. FIG. 5 illustrates a frontview of a valve prosthesis 60. FIG. 6 illustrates a top view of valveprosthesis 60. Valve prosthesis 60 includes a valve body 62 supportedwithin a frame 64. Frame 64 includes an inlet portion 66, an hourglassshaped central portion 68 and support arms 70. Support arms 70 can beconfigured to capture leaflets during delivery of prosthesis 60. Centralportion 68 can pinch a muscular ridge of the native annulus. Thehourglass shape of frame 64 can be located on central portion 68 aroundthe entire circumference of frame 64. One example of such aconfiguration is shown in FIGS. 5-6. Other suitable configurations canbe used. Frame 64 can also provide axial fixation by creating chordaltension of chordae.

FIGS. 7, 8, and 9 a-9 b illustrate a frame 72. FIG. 7 illustrates afront view of a frame 72. FIG. 8 illustrates a top view of a valveprosthesis 74 including a valve body 76 supported by frame 72. FIG. 9aillustrates a view of valve prosthesis 74 implanted in a native valvesite 78. FIG. 9b is an enlarged view of a portion of FIG. 9a . Valvesite 78 includes annulus 80, chordae 82, and papillary muscles 84.

Frame 72 includes an inlet portion 86, an hourglass shaped centralportion 88 and support arms 90. Support arms 90 are configured tocapture leaflets during device delivery. Axial fixation of frame 72 canbe achieved through the hourglass shaped central portion 88 pinching amuscular ridge of the native annulus. Frame 72 can have an ellipticaloutflow end 92. The larger diameter of the ellipse can be positionednear the mitral valve commissures of the native valve. The shorter partof the ellipse can be near the aorto-mitral fibrous continuity of thenative valve. Although outflow end 92 can be elliptical, valve body 76of frame 72 can remain cylindrical. One example of such a configurationis shown in FIGS. 7-9. Other suitable configurations can be used. Frame72 can also provide axial fixation by creating chordal tension ofchordae 82.

FIGS. 10-11 illustrate a valve prosthesis 94. FIG. 10 illustratesbottom-front perspective view of valve prosthesis 94 in an openposition. FIG. 11 illustrates a bottom-front view of valve prosthesis 94in a closed position. Valve prosthesis 94 includes a frame 96 along witha valve body including prosthetic leaflets 98. An outflow end 104 offrame 96 flares outwardly to allow for gaps 100 between an outflow end102 of leaflets 98 and outflow end 104 of frame 96.

FIGS. 12-13 illustrate a valve prosthesis 105. FIG. 12 illustrates abottom-front view of valve prosthesis 105 in an open position. FIG. 13illustrates a bottom view of valve prosthesis 105. Valve prosthesis 105includes a frame 106 along with a valve body including prostheticleaflets 107. As shown, for example in FIG. 13, a cross-section of avalve outlet 111 is a rounded triangle with each vertex 112 of thetriangle aligned with a corresponding leaflet 107 of the valve body toprovide gaps 108 between an outflow end 110 of frame 106 and the outflowend 109 of leaflet 107 when leaflet 107 is fully open. In someembodiments, the mid-section of sides 113 of frame 106 are aligned withcorresponding commissures 114 of the valve body.

The cross-section of a valve base 115 can be a rounded triangular androtated about 60 degrees relative to the cross-section of valve outlet111 so that the body forms a roughly cylindrical shape. One example ofsuch a configuration is shown in FIG. 13. Other suitable configurationscan be used.

FIGS. 14-15 illustrate a valve prosthesis 120. FIG. 14 illustrates valveprosthesis 10 in an open position. FIG. 15 illustrates a bottom view ofvalve prosthesis 120. Valve prosthesis 120 includes a frame 122 alongwith a valve body including prosthetic leaflets 124. Frame 122 isconfigured to allow for gaps 126 between an outflow end 128 of leaflets124 and an outflow end 130 of frame 122 when leaflets 124 are fullyopen. In some embodiments, gaps 126 can be sized and shaped to minimizeor eliminate contact between leaflets 124 and frame 122. In someembodiments, gaps 126 can be up to 5 millimeters wide. In someembodiments, gaps 126 can be larger than 5 millimeters. In someembodiments, the mid-section of sides 132 are aligned with correspondingcommissures 138 of the valve body.

Sides 132 of the rounded triangle of valve outlet 134 curve inward. Theoverall shape of the cross-section of valve outlet 134 can be describedas clover-leaf shaped. In addition, sides 132 of the rounded triangle ofvalve base 136 curve inward and can also be described as clover-leafshaped. The cross-section of valve base 136 can be rotated about 60degrees relative to the cross-section of valve outlet 134 so that thevalve forms a roughly cylindrical shape. In some embodiments, valve base136 can be substantially cylindrical and valve outlet 134 can flare outfrom valve base 136. In some embodiments, leaflets 124 can be attachedat valve base 136. Other suitable configurations can be used.

FIG. 16a illustrates a frame 140. A non-planar shape of one or more ofthe various frames described herein can be achieved by changing thelocation of nodes formed within the frame. For example, a laser cutpattern of a frame can be modified, along with new fixtures for heatseating to achieve such a configuration. In particular, frame 140includes nodes 142 arranged in a sinusoidal pattern. In someembodiments, such a configuration can have the effect of changing theshape of frame 140 when frame 140 is expanded. The sinusoidal pattern ofnodes 142 within frame 140 can, for example, result in a threedimensional saddle shape 144 of frame 140, shown for example in FIG. 16b, that can mimic the native anatomy at a mitral annulus. In someembodiments, frame 140 can include a modified inflow section 143 and anunmodified valve section 145.

FIGS. 17-18 illustrate a frame 146 for a valve prosthesis. FIG. 17illustrates a front view of frame 146. FIG. 18 illustrates a top view offrame 146. Frame 146 includes central portion 162, inlet portion 168,and chordae guiding element 148. Chordae guiding element 148 extendsfrom support arm 150 and is configured to engage chordae of the nativevalve site. As described above, chordae can connect to native leafletsand act like “tie rods” in an engineering sense. Not only can thechordae help prevent prolapse of the native leaflets during systole,they can also help support the left ventricular muscle mass throughoutthe cardiac cycle. In some embodiments, it can be desirable to imparttension onto the chordae with support arms, such as support arms 150.However, excessive tension can cause the chordae to rupture which canreduce the effectiveness of valve prosthesis 156. In some embodiments,the shape and location of support arms 150 on frame 146 can reducetension imparted onto the chordae by support arms 150.

In some embodiments, chordae guiding element 148 can be formed by arigid wire material and can be shaped to avoid hard angles and/or sharpedges. In some embodiments, chordae guiding element 148 can be the samethickness and material as support arm 150. In some embodiments, chordaeguiding element 148 can be bent in the shape of a semi-circle, oval,lobe, or other suitable shape. Chordae guiding element 148 can beconfigured to angle chordae 152 so that the chordae are stretched torestrict movement of valve prosthesis 156 in a downstream direction ofblood flow at valve site 154.

In some embodiments, chordae guiding element 148 can be configured tointeract with one or more native leaflets instead of the chordae. Insome embodiments, one or more of the above configurations can be used incombination with other coatings, coverings, or configurations to reducechordal abrasion or rupture. In some embodiments, the corners of one orboth of support arm 150 and chordae guiding elements 148 can be rounded,which in some embodiments can avoid sharp corners that can cause chordalabrasion or rupture.

In some embodiments, chordae guiding element 148 is positioned such thatchordae 152 are stretched to prevent movement of valve prosthesis 156relative to the native valve over the course of the cardiac cycle,without rupturing chordae 152. In some embodiments, such a configurationcan provide added stability to valve prosthesis 156 while preventingdamage to chordae 152.

In some embodiments, chordae guiding element 148 can be directlyattached to support arm 150 and can extend outward from the leafletsecuring arm. A first end and a second end of chordae guiding element148 can be attached to a central portion 162 of frame 146. In someembodiments, one end of chordae guiding element 148 can be directlyattached to support arm 150 and a second end of chordae guiding element148 can be directly attached to central portion 162. In someembodiments, chordae guiding element 148 can reduce bending of thenative chordae by redistributing the force applied by support arm 150 tochordae 152.

In some embodiments, an outflow end 164 of support arm 150 islongitudinally offset from an outflow end 166 of chordae guiding element148 by a distance to reduce the bending of chordae 152. The longitudinaloffset can, for example, be from about 1 mm to about 5 mm in thelongitudinal direction.

In some embodiments, outflow end 164 of support arm 150 is laterallyoffset from outflow end 166 of chordae guiding element 148 by a distanceto reduce the bending of chordae 152. The lateral offset can, forexample, be from about 1 mm to about 5 mm in the lateral direction.

In some embodiments, chordae guiding element 148 can be configured tocreate a tapered entry for chordae. In some embodiments, a longitudinaland/or lateral offset between support arms 150 and chordae guidingelement 148 can be configured to guide chordae substantially along aportion of an arc, such as along a portion of parabolic arc 151 (shownin broken lines) in FIG. 17. In some embodiments, arc 151 can becircular rather than parabolic, stepped, or another desired shape. Insome embodiments, arc 151 can guide chordae exiting support arm 150 andchordae guiding element 148 to approximate a native anatomical angle. Insome embodiments, such a configuration can reduce abrasion of thechordae and/or maintain a desired chordal tension. In some embodiments,a desired chordal tension is sufficient to prevent frame 146 fromlifting into the atrium. In some embodiments, a desired chordal tensionis sufficient to substantially prevent frame 146 from moving and/orrocking during the cardiac cycle.

In some embodiments, the angle formed by arc 151 can serve to decreasean angle of entry of the chordae into support arm 150, which can reducechordal abrasion forces acting on the chordae from frame 146. In someembodiments, support arms 150 and chordae guiding element 148 areconfigured to substantially eliminate bending of the chordae. In someembodiments, support arms 150 and chordae guiding element 148 areconfigured to bend the chordae less than approximately 90 degrees. Insome embodiments, chordae are guided solely by chordae guiding element148 and are guided by chordae guiding element so as not to touch supportarms 150.In some embodiments, a second support arm 170 can connect toand extend from central portion 162 and can be configured to extend overand engage a second native leaflet of the native valve. A second chordaeguiding element can also be connected to second support arm 170 and canbe configured similarly to first support arm 150.

FIG. 19 illustrates a simplified drawing of a support arm 172. Supportarm 172 can include a first end 173 and a second end 175. One or both offirst end 173 and second end 175 can be connected to the same ordifferent portions of the frame (not shown). Support arm 172 includes afirst and second chordae guiding element 174, which can functionsimilarly to the chordae guiding elements described above. Each chordaeguiding element 174 can include a first end 176 attached to support arm172 and a second end 178 attached to the frame. In some embodiments,first end 176 can be connected to the frame. In some embodiments, bothfirst end 176 and second end 178 can be connected to support arm 172.

One or more of the valve prostheses described herein can be implantedinto an annulus of a native cardiac valve through a suitable deliverymethod. For example, the valve prosthesis can be implanted throughconventional open-heart surgery techniques. In some embodiments, thevalve prosthesis can be delivered percutaneously. For example, in somepercutaneous techniques, valve prosthesis can be compacted and loadedonto a delivery device for advancement through a patient's vasculature.The valve prosthesis can be delivered through an artery or vein, afemoral artery, a femoral vein, a jugular vein, a subclavian artery, anaxillary artery, an aorta, an atrium, and/or a ventricle. The valveprosthesis may be delivered via a transfemoral, transapical,transseptal, transatrial, transventrical, or transaortic procedure.

In some embodiments, the valve prosthesis can be deliveredtransfemorally. In such a delivery, the delivery device and the valveprosthesis can be advanced in a retrograde manner through the femoralartery and into the patient's descending aorta. A catheter can then beadvanced under fluoroscopic guidance over the aortic arch, through theascending aorta, into the left ventricle, and mid-way across thedefective mitral valve. Once positioning of the catheter is confirmed,the delivery device can deploy the valve prosthesis within the annulus.The valve prosthesis can then expand against and align the prosthesiswithin the annulus. In some embodiments, as the valve prosthesis isexpanded, it can trap leaflets against the annulus, which can retain thenative valve in a permanently open state.

In some embodiments, the valve prosthesis can be delivered via atransapical procedure. In a transapical procedure, a trocar or overtubecan be inserted into a patient's left ventricle through an incisioncreated in the apex of the patient's heart. A dilator can be used to aidin the insertion of the trocar. In this approach, the native valve (forexample, the mitral valve) can be approached from the downstreamrelative to the blood flow. The trocar can be retracted sufficiently torelease the self-expanding valve prosthesis. The dilator can bepresented between the leaflets. The trocar can be rotated and adjustedto align the valve prosthesis in a desired alignment. The dilator can beadvanced into the left atrium to begin disengaging the proximal sectionof the valve prosthesis from the dilator.

In some embodiments, the valve prosthesis can be delivered via atransatrial procedure. In such a procedure, a dilator and trocar can beinserted through an incision made in the wall of the left atrium of theheart. The dilator and trocar can then be advanced through the nativevalve and into the left ventricle of heart. The dilator can then bewithdrawn from the trocar. A guide wire can be advanced through thetrocar to the point where the valve prosthesis comes to the end of thetrocar. The valve prosthesis can be advanced sufficiently to release theself-expanding frame from the trocar. The trocar can be rotated andadjusted to align the valve prosthesis in a desired alignment. Thetrocar can be withdrawn completely from the heart such that the valveprosthesis self-expands into position and can assume the function of thenative valve.

The choice of materials for the various valve prostheses describedherein can be informed by the requirements of mechanical properties,temperature sensitivity, biocompatibility, moldability properties, orother factors apparent to a person having ordinary skill in the art. Forexample, one more of the parts (or a portion of one of the parts) can bemade from suitable plastics, such as a suitable thermoplastic, suitablemetals, and/or other suitable materials.

The foregoing description of the invention has been presented forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise form disclosed.Other modifications and variations can be possible in light of the aboveteachings. The embodiments and examples were chosen and described inorder to best explain the principles of the invention and its practicalapplication and to thereby enable others skilled in the art to bestutilize the invention in various embodiments with modifications as aresuited to the particular use contemplated. It is intended that theappended claims be construed to include other alternative embodiments ofthe invention.

The invention claimed is:
 1. A valve prosthesis comprising: a frameincluding a central portion, a support member extending from the centralportion, the support member including a leaflet engagement portionconfigured to engage a native valve leaflet and a chordae engagementportion configured to engage and tension at least one native chorda tothereby restrict movement of the valve prosthesis in an upstreamdirection of blood flow, wherein an outflow end of the leafletengagement portion is laterally offset from an outflow end of thechordae engagement portion, and an inlet portion extending radiallyoutward from the central portion and configured to engage a floor of anoutflow tract of a native heart atrium to thereby restrict movement ofthe valve prosthesis in a downstream direction of blood flow; and aprosthetic valve secured to the central portion.
 2. The valve prosthesisof claim 1, wherein the support member and the inlet portion act inopposition to create a seal between the inlet portion and a floor of anoutflow tract of a native heart atrium after implantation of the valveprosthesis.
 3. The valve prosthesis of claim 2, wherein the seal ismaintained throughout a cardiac cycle of a patient.
 4. The valveprosthesis of claim 2, wherein the seal is maintained during changes inchordal tension throughout a cardiac cycle of a patient.
 5. The valveprosthesis of claim 1, wherein at least a portion of the inlet portionhas a flexibility of between 0.8 N/m to 2 N/m.
 6. The valve prosthesisof claim 1, wherein a cross-section of the inlet portion issubstantially s-shaped.
 7. The valve prosthesis of claim 1, wherein atleast a portion of the frame is self-expandable.
 8. The valve prosthesisof claim 1, wherein at least a portion of the frame isballoon-expandable.
 9. The valve prosthesis of claim 1, wherein thesupport member of the frame comprises multiple support members.
 10. Thevalve prosthesis of claim 9, wherein each support member comprises atleast one engagement portion configured to engage and tension at leastone native chorda to thereby restrict movement of the valve prosthesisin an upstream direction of blood flow.
 11. The valve prosthesis ofclaim 1, wherein the inlet portion is configured to deform a floor of anoutflow tract of a native heart atrium.
 12. The valve prosthesis ofclaim 1, wherein the inlet portion is configured to engage an atrialwall.
 13. The valve prosthesis of claim 1, wherein the central portionis configured to conform to a native annulus.
 14. The valve prosthesisof claim 1, wherein the central portion has an hourglass-shape.
 15. Thevalve prosthesis of claim 1, wherein the chordae engagement portion isconfigured to angle the at least one native chorda so that the at leastone native chorda is stretched.
 16. The valve prosthesis of claim 1,wherein the leaflet engagement portion is a support arm having a firstend directly attached to the central portion and a second end directlyattached to the central portion.
 17. The valve prosthesis of claim 16,wherein the chordae engagement portion has a first end directly attachedto the support arm and a second end directly attached to the supportarm.
 18. The valve prosthesis of claim 16, wherein the chordaeengagement portion has a first end directly attached to the support armand a second end directly attached to the central portion.
 19. The valveprosthesis of claim 16, wherein the chordae engagement portion has afirst end directly attached to the central portion and a second enddirectly attached to the central portion.
 20. The valve prosthesis ofclaim 1, wherein the outflow end of the leaflet engagement portion isalso longitudinally offset from the outflow end of the chordaeengagement portion.